An “ex-Microsoft designer” nerdsplains everybody's favorite UI element, the hamburger:
“What the research is showing is that people aren’t actually as wedded to one handed use as we used to believe they are. Don’t get me wrong, this is clearly a tradeoff. Frequently used things have to be reachable, even one-handed. But hamburgers are not frequently used, and one-handed use is not ironclad. Combine those two factors together and you see why the industry has settled on this standard. It wasn’t random … And, sorry. But the hamburger has some real issues, but ‘I can’t reach uncommon things without adjusting my hand on my massive phone and that annoys me because it reminds me of the dominant OS on earth” [is not one of them].
I never get complaining about having to use two hands while doing computery things on that computer you're using, I mean, even when smartphones were just cellphones, you had to use two hands to call somebody.
BTW, lot's more on the hamburger and Windows Phone at that link above.